Typically, tufted carpeting is produced by stitching a plurality of rows of yarn loops through a previously-manufactured mesh-like backing so that the yarn protrudes above one face of the backing as a pile, and is drawn relatively closely against the opposite face of the backing. The pile, formed as yarn loops may be permitted to remain as loops, or it may be sheared or otherwise cut to create a cut pile rather than a looped pile. It is necessary to perform a further operation on the as-tufted product in order to lock the pile in place. Otherwise, even slight pulling on any of the loops or tufts of pile yarn will separate the yarn from the backing. In instances in which the pile is cut pile, pulling can separate individual tufts leaving naked spots, and in instances in which the pile is uncut pile, pulling on one loop can create a snag leaving a whole row or a segment of row as a naked strip on the carpet face. By far the heretofore most popular way of locking the tufted yarn to the backing has been to apply an adhesive to the back of the backing, after tufting, in such a manner as to adhere the back loops of the yarn to the backing, mechanically entrap the back loops of the yarn in a common matrix with the backing, and in order to obscure access to the back loops.
As may be imagined, there are many variations in the constituency of tufted carpets, and in the processes and apparatus used for making tufted carpeting. For instance, some tufted carpeting is made by stitching yarn through two or more layers of backing, e.g. having two or more different gauges (number of picks per inch); see the Avery U.S. Pat. No. 4,426,415, issued Jan. 17, 1981. Multiple backings, when used, can strengthen the product, stiffen it, provide additional holding power against pulling-out of stitches, help to hold the face pile upright and help prevent back-coating composition from flowing excessively into the face pile as it is applied to the back.
In some instances the or a layer of the backing is made of flexible plastic film or non-woven fabric, rather than a fabric mesh. In some instances the coating which is applied to the underside of the backing doubles in function as a non-slip surface-providing means; in other instances, the stitch-locking coating is itself backed with one or more layers of woven fabric, plastic film, non-woven fabric and/or a non-slip feature-providing coating. Backings are made from a variety of materials, including, without limitation, natural materials typified by jute, and synthetic polymeric materials typified by polypropylene. Backings are made of varous weights, gauges and weaves.
For some applications, it is desirable that the combination of the backing layer or layers, the back-loops of the tufted yarn, the stitch-locking layer and additional layers provide a substantially continuous barrier separating the face of the carpet from the base on which the carpet is laid. For other applications the exact opposite--porosity through the carpeting from face to underside--is desirable or, indeed, essential.
A particularly popular use of tufted carpeting is as artificial turf, both for playing surfaces for the conduct of sports activities such as football, baseball, soccer and the like, and for landscaping or decorating various indoor and outdoor sites.
A recent practice in the use of artificial turf has involved the spreading of sand, soil, or some other filler material onto the surface of the turf. The purpose of the filler material is to provide a playing surface which is more closely similar to natural (grass/soil) playing surfaces. Artificial turf, as presently produced, does not allow sufficient quantities of filler material to be worked into the turf, does not allow for proper drainage of water from the surface, and erodes (wears out) too quickly when used with most filler materials.